Pour-point depressor



Dec. 6, 1955 A. w. WEITKAMP ET AL POUR-POINT DEPRESSOR 3 Sheets-Sheet 1 Filed Aug. 51 1950 Commercial Range Un freazed Pourex W m J w w 0.5 0.0 POUREX 40050, VOL. 7.

0! T N WWW? Nk 4 wil W 94; s m W f Y mw 5 Dec. 6, 1955 A. w. WEITKAMP ET AL POUR-POINT DEPRESSOR 3 Sheets-Sheet 2 Filed Aug. 31, 1950 d m n w M; P WW d o a k p w w m U Commercial Range I 1 i i I 1 i 1 i i l I l g l 5 E I i i I I l s i I 1 I l 1 i t 28m qboqu POUREX ADDED, VOL. 70

Willard S. H/g/e y BY Ma /244% TAG-ROBINSON COLOR INDEX 6, 955 A. w. WEITKAMP ETAL 2,725,212

POUR-POINT DEPRESSOR Filed Aug. 31, 1950 3 Sheets-Sheet 3 Range I l I l I I l I I I I l Urea Tre afe o Unfreofed Pourex I I I I I I I I 0 0. I 0.2 0.3 0.4 0.5 0.6 0.7 0.8

POURE X ADDED, VOL.

, INVENTORS:

. Alfred W Weifkamp 3 Willard S. Hllgley By W 9' 514421 2,726,212 Patented Dec. 6, 1955 POUR-POINT DEPRESSOR I Alfred W. Weitkamp, Lansing, 111., and Willard S. Higley, Hammond, Ind., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application August 31, 1950, Serial No. 182,550

4 Claims. (Cl. 252-73) This invention relates to pour-point depressors, and more particularly to pour-point depressors of the type produced by reacting a chlorinated wax with an aromatic hydrocarbon in the presence of a Friedel-Crafts catalyst.

Pour-point depressors have been used for many years to reduce the tendency of lubricating oils to congeal at low temperatures, to solidify in oil lines, and to render starting of engines difficult in cold weather. Numerous types of pour-point depressors have been developed, but the most successful are the long-chain alkylated aromatic compounds, illustrated by such products as Paraflow, described in U. S. Patent 1,815,022, and Pourex, described in U. 8. Patents 1,963,917 and 1,963,918. These materials are prepared by chlorinating a wax, such as parafiin wax, petrolatum, montan wax, ozocerite wax, or a heavy hydrocarbon oil, and contacting the chlorinated wax with an aromatic hydrocarbon such as naphthalene, diphenyl, chlorinated diphenyl fluorene, phenanthrene, anthracene, or coal-tar residues in the presence of a Friedel-Crafts catalyst, preferably aluminum chloride. The products are dark, amorphous materials of remarkable effectiveness in depressing the pour-point of lubricating oils. V

We have now discovered a method for improving the aforesaid long-chain alkylated aromatic pour-point depressors. In our new method, a pour-point depressor of the said group is contacted with urea, and the urea is subsequently separated therefrom, taking with it impurities of unknown nature and leaving a pour-point depressor of greatly improved color and of improved effectiveness with respect to its ability to lower the pourpoint and the cloud-point of lubricating oils.

One object of our invention is to prepare a pour-point depressor of increased eifectiveness in reducing the pourpoint of lubricating oils. Afurth er object is to improve the color of long-chain alkylated aromatic pour-point depressors. A further object is to prepare a pour-point depressor having the property of reducing the cloud-point of lubricating oils. A still further object is to prepare a stock solution of an improved pour-point-depressor, said stock solution having a low pour point. Other objects of our invention and its advantages over the ,prior art will be apparent from the following description and illustrative examples.

A suitable method for preparing a pour-point depressor of the type to which our invention is directed is described by Frederick H. MacLaren in U. S. Patent 1,963,918, referred to above. The method comprises heating a mixture of a chlorinated parafiin wax and naphthalene to a temperature between about 25 and 350 F., subsequently adding about 3to'10 percent by weight of aluminum the reaction mixture until the reaction has subsided (from 2 to 20 minutes ordinarily being required), separating aluminum chloride sludge from the reaction mixture, washing the reaction product with aqueous soda ash solution to remove acids therefrom, washing the neutralized reaction products with water, and drying. The resulting product, termed Pourex base in commercial terminology, is ordinarily diluted with a suitable solvent such as 1 Mid-Continent SAE lubebase oil, 0203 Oil (a 'Midcarbons such as chloroform, carbon tetrachloride, tetradition to avoid an excessive rate of reaction) agitating Continent base turbine oil, dewaxed, reduced, treated, and contact filtered; viscosity approximately 200 SSU at 100 F.), Kittrell transformer oil, or the like beforebeing added to lubricating oils.

In carrying out our invention, the crude pour-point depressor is commingledwith about 1 to percent by weight of urea, ordinarily about 5 to 20 percent, and about 0.1 to 10 moles of urea solvent per mole of urea. A saturated solution of urea in methanol can be used conveniently, the molar ratio of methanol to urea therein being about 9. The mixture is agitated vigorously at a temperature between about 32 and 140 F., preferably between about 70 and F., for approximately 0.1 to 2.0 hours. Under these conditions, the urea appears to react and form solid addition compounds with waxy impurities ,and to a lesser extent with colored bodies and other impurities existing in the charging stock, so that such impurities may subsequently be withdrawn as apart of the reaction solids. The solids are removed from the reaction product in a known manner, such as by filtration, settling and decantation, centrifugation, or the like. The liquid material remaining after the separation of the reaction solids is our improved pour-point depressor having a much lighter color and a greatly improved effectiveness for reducing the pour-point and the cloud-point of lubricating oils.

Since our charging stock is ordinarily a very viscous material, we prefer to dissolve it in a suitable diluent liquid in order to facilitate the contact of the material with urea. The diluent should be a solvent for the charging stock, a non-solvent for urea, and unreactive with urea. Suitable diluents include aromatic hydrocarbons such as benzene, toluene, xylenes, and the like; naphthenes such as cyclopentane, cyclopentene, cyclohexane,

hydrocarbons such aspentane, isopentane, hexane, neohexane, and the like; and chlorinated aliphatic hydrochloroethylene, ethylene dichloride, and the like. We

may also use conventional lubricating oils and lube-oil bases as solvents in place of the above volatilesolvents.

Urea may be used in our process in the form of the 7 solid crystalline compound, or as a slurry in a urea solvent, or as a saturated solution in a urea solvent. We prefer, however, to employ the solid crystalline urea. A quantity of urea solvent should be incorporated in the reaction mixture to activate the reaction of urea with the impurities in our charging stock. Among such solvents are water, acetone, methyl ethyl ketone, acetaldehyde, propionaldehyde, and the like; but we prefer to uselower aliphatic (C1 to Cs) alcohols such as methanol, ethanol, isopropyl alcohol, and the like. The urea solvent is preferably used inthe proportion of from 0.1 to 1.0 mole per mole of urea.

The solids that are separated from the reaction product in our process consist essentially of unreacted urea and urea addition products of unknown composition. The urea may be recovered therefrom in a known manner by extraction with water. The urea is obtained thereby as an aqueous solution, and may subsequently be recovered by conventional methods in a form suitable for reuse. Alternatively, the addition products may be decomposed by treatment with a hot solvent for the impurities contained therein, or by treatment with an organic solvent for urea, or by a combination process employing an organic solvent such as toluene and a urea solvent such as water, the process being carried out at elevated temperature and pressure if necessary to eifect the desired decomposition.

Our invention will be more fully understood from the following specific examples.

Example I Neutralized Pourex base (Batch No. 151, Reactor No. 3) was prepared as described in MacLaren U. S. Patent 1,963,918, referred to above, according to the following procedure: Four hundred gallons of petroleum wax having a melting range of l30l32 F. and a specific gravity of 52 API at 170 F. were charged into a reaction vessel and heated to 200 F. Chlorine was then dispersed in the wax at 200 F. until the specific gravity of the reaction mixture had reached 31 API at 170 F. Thereafter, 332 pounds of naphthalene were added, followed by 66 pounds of aluminum chloride in 0.5-pound increments over a period of 24 hours at 200 F. At the end of the 24-hour reaction period, the reaction mass was cooled to 170 F. and neutralized with aqueous 17 per cent ammonium hydroxide. The resulting neutralized Pourex base had a softening point of approximately 100 F., and was dark brown in color, with a green cast. A 0.7 percent by weight solution thereof in SAE Base Oil had a Tag- Robinson color index of 11.7, and a 1 percent by weight solution in a white oil had a Tag-Robinson color index of 17.

The neutralized Pourex base (50 grams), urea (40 grams), methanol (165 milliliters), and pentane (350 milliliters) were mixed and agitated at 70 F. for one hour. The resulting reaction product was filtered, the filtrate was stripped of pentane, and 37.3 grams of a translucent jelly-like residue were obtained. This material (referred to hereinafter as urea rafiinate) was a viscous, heavy oil at 25 C., whereas a quantity of untreated Pourex base which, for comparison, had been slurried with pentane, filtered, and stripped, was a greasy solid of the consistency of petrolatum. Both specimens of Pourex base were made up into stock solutions of 16 percent by weight in 0203 oil (defined above). The

urea-treated Pourex base stock solution had a pour point of -25 F., whereas the untreated Pourex base stock solution had a pour point of F.

The solids obtained from the urea reaction product were agitated in a closed reactor bomb with 800 milliliters of water and 200 milliliters of toluene at 265 F. for

90 minutes. The hot toluene layer was separated, filtered, and stripped free of toluene, and 9.8 grams of solid residue of unidentified composition (termed urea extract hereinafter) were obtained.

For comparative tests on the original Pourex base (which had been diluted, filtered, and reduced as described above) and on the urea partition fractions described above, stock solutions were prepared by incorporating 16 percent by weight of each of the various materials in Kittrell Transformer Oil. The urea rallinate gave a clear, transparent solution, whereas the untreated Pourex base gave the usual opaque solution. Comparative tests were made by incorporating 1 percent by weight of the said stock solutions (equivalent of 0.16 percent by weight of the undiluted materials) in two different petroleum oils.

The following table illustrates the superiority of our improved pour-point depressor when incorporated in an SAE 20 base oil (a distillate fraction from 38 percent Mid-Continent reduced crude, said fraction having been phenol-extracted and propane-dewaxed to reduce its pour point to 0 F.).

Pour Cloud Additive Point, Point.

None 0 +8 Pourcx base 0 t) Urea extract.. +5 12 Urea raifinate 5 8 The following table shows the effect of our improved pour-point depressor in Premier White ()il.

Pout Cloud Additive Point, Point.

I I. i None 1 +34 Pourex base" 0 36 Urea extract. +25 40 Urea ratfinate -15 32 Example Il Treated Pourex Untreated Pourex 9%11CeIlt-1f ttigll of i onrex use, Pour 010m} Pour Cloud I Percem Point, Point, Golor Point, 1 Point, 1 Color F. F. I". F.,

1 Tag-Robinson Index.

The foregoing data are presented graphically in Figures 1, 2, and 3. From Figure 1, it is evident that urea-treated Pourex when used in the commercial range (0.16 to 0.24 percent by weight) produces a pour point approximately 10 F. lower than untreated Pourex. Similarly, in the same concentration range, the cloud point is approximately 4 F. lower, and the color index is about 2 units lower.

While we have described our invention with reference to certain specific charging stocks and manipulative procedures, it will be apparent that our invention is not restricted thereto, but is to be construed broadly within the terms of the disclosure and claims. It is further to be understood that any modifications or equivalents that would ordinarily occur to one skilled in the art are to be considered as lying within the scope of our invention.

In accordance with the foregoing description, we claim as our invention:

1. A method for improving a pour-point depressor obtained by reacting a chlorinated wax with an aromatic hydrocarbon in the presence of a Friedel-Crafts catalyst,

which comprises contacting said pour-point depressor with urea and a urea solvent and separating the solids from the resulting reactionmixture, whereby a pour-point depressor of improved effectiveness is obtained.

2. A method for improving a pour-point depressor obtained by reacting a chlorinated wax with an aromatic hydrocarbon in the presence of a Friedel-Crafts catalyst, which comprises contacting said pour-point depressor with between about 1 and percent by weight of urea, based on said pour-point depressor, and a urea solvent and sepa- 3. A method for improving a pour-point depressor obtained by reacting a chlorinated parafiin Wax with naphthalene in the presence of aluminum chloride, which comprises contacting said pour-point depressor at a temperature between about 32 and 140 F. with between about 5 and 20 percent by Weight of urea, based on said pour-' point depressor, and a lower aliphatic alcohol and separating the solids from the resulting reaction .rnixture, whereby a pour-point depressor of improved effectiveness is obtained.

4. A method for preparing a low pour-point stock solution of a pour-point depressor obtained by reacting a chlorinated wax with an aromatic hydrocarbon in the presence of a Friedel-Crafts catalyst, which comprises diluting said pour-point depressor with a lube-oil base, contacting the resulting solution with between about 1 and 70 percent by weight of urea, based on said pour-point depressor, and a urea solvent and separating the solids from the resulting reaction mixture, whereby a stock-solw tion of said pour-point depressor is obtained having a lower pour point and improved effectiveness as a pourpoint depressor. I

References Cited in the file of this patent UNITED STATES PATENTS Arnold et al Aug. 5, 1952 OTHER REFERENCES Zimmershied: Jour. Am. Chem. Soc., vol. 71, 2947 (1949).

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4. A METHOD FOR PREPARING A LOW POUR-POINT STOCK SOLUTION OF A POUR-POINT DEPRESSOR OBTAINED BY REACTING A CHLORINATED WAX WITH AN AROMATIC HYDROCARBON IN THE PRESENCE OF A FRIEDEL-CRAFTS CATALYST, WHICH COMPRISES DILUTING SAID POUR-POINT DEPRESSOR WITH A LUBE-OIL BASE, CONTACTING THE RESULTING SOLUTION WITH BETWEEN ABOUT 1 AND 70 PERCENT BY WEIGHT OF UREA, BASED ON SAID POUR-POINT DEPRESSOR, AND A UREA SOLVENT AND SEPARATING THE SOLIDS FROM THE RESULTING REACTION MIXTURE, WHEREBY A STOCK-SOLUTION OF SAID POUR-POINT DEPRESSOR IS OBTAINED HAVING A LOWER POUR POINT AND IMPROVED EFFECTIVENESS AS A POURPOINT DEPRESSOR. 